One vertex per element, one color per generator, with an edge from x to x·s.
(6,8)(10,11)(13,14)(15,20)(16,19)(17,18)(23,24)(26,27) involution — undirected(2,4)(5,6)(7,11)(8,9)(10,12)(14,18)(19,20)(21,22,25,28)(23,26,24,27)(1,2)(3,4)(6,8)(10,11)(13,15,17,16)(14,19,18,20)(21,23,25,24)(22,26,28,27)(5,7,9,12)(6,10,8,11)(13,16,17,15)(14,20,18,19)(21,22)(23,26)(24,27)(25,28)(5,8,9,6)(7,10,12,11)(13,14)(15,20)(16,19)(17,18)(21,24,25,23)(22,27,28,26)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.